The U.S. Department of Agriculture said it has banned farmers from planting popular Clearfield CL131 rice seeds made by BASF Corp. (BF) this year after the government confirmed the presence of an unapproved biotech trait in seed supplies.

Seed produced for 2005, 2006 and 2007 crops is not to be planted, USDA said. Furthermore, USDA is demanding that farmers who have already planted Clearfield CL131 rice destroy the crops either by treating it with chemicals or "mechanically destroying the plants after emergence."

USDA spokesman Keith Williams said he believes the amount of farmers who already planted is "very, very, few," but did not give any numbers.